Separation of rotamers of 5-nitrosopyrimidines and estimation of binding constants of their complexes with ß-cyclodextrin by capillary electrophoresis.
J Chromatogr A
; 1570: 164-171, 2018 Oct 05.
Article
in En
| MEDLINE
| ID: mdl-30082126
ABSTRACT
For the first time, capillary electrophoresis has been successfully employed for the fast and highly efficient separations of a novel type of stereoisomers - planar rotamers (planamers) of four newly synthesized 5-nitrosopyrimidine derivatives. These derivatives can form two rotamers differing in the orientation of nitroso group due to strong intramolecular hydrogen bonds. Partial separation of rotamers of two 5-nitrosopyrimidines was achieved in alkaline 50 mM sodium tetraborate, pH 9.3, and in acidic 18.5/42 mM Tris/phosphate, pH 2.3, background electrolytes (BGEs) free of stereoselectors. To improve the separation of these rotamers and to attain the baseline or better separation of rotamers of other two 5-nitrosopyrimidines, various BGEs and different cyclodextrins-based stereoselectors were tested. The most effective, i.e. the fastest and baseline or better separations of rotamers of all analyzed 5-nitrosopyrimidines were achieved within a short time, 3.7-9.3 min, in the above alkaline or acidic BGEs using ß-cyclodextrin (ß-CD) or carboxymethyl-ß-CD as stereoselectors. Moreover, since the experiments with ß-CD resulted in good separations of rotamers of all the investigated 5-nitrosopyrimidines, the apparent binding constants of their complexes with this selector were determined from the dependence of their effective mobilities on the ß-CD concentration in the BGEs. The examined complexes were found to be relatively weak, with the apparent binding constants in the range 11.3-153.0 L/mol.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Pyrimidines
/
Electrophoresis, Capillary
/
Beta-Cyclodextrins
/
Nitroso Compounds
Language:
En
Journal:
J Chromatogr A
Year:
2018
Document type:
Article